The present invention relates to a CPU heat sink mounting arrangement which comprises a circuit board, a positioning plate and a heat sink attached to the circuit board at two opposite sides, and two locking plates installed in the heat sink and fastened to upright rods at the positioning plate to secure the heat sink, the circuit board and the positioning plate together, enabling the heat sink to be maintained in close contact with a CPU at the circuit board.
When the CPU (Central Processing Unit), for example, PENTIUM II from Intel at the main board in a computer is operated, it produces much heat. It is well known that excessive high temperature affects normal operation of the CPU. Therefore, heat must be quickly carried away from the CPU during the operation of the computer. FIG. 8 shows a CPU heat sink mounting arrangement for this purpose. This design was intended by the present inventor, and is comprised of a heat sink, a circuit board carrying a CPU, two coupling plates, and two substantially L-shaped locking plates (only one locking plate is shown). The heat sink comprises four headed mounting rods respectively inserted through respective through holes at the circuit board and respective coupling holes at each of the coupling plates. The locking plates are respectively fastened to the headed mounting rods to lock the heat sink, the circuit board and the coupling plates together. The locking plates each have an elongated slot longitudinally extended to one end, and two keyway-like locating holes formed integral with the elongated slot for engagement with the head of each of the headed mounting rods of the heat sink. This structure of CPU heat sink mounting arrangement is functional, however it still has drawbacks. Because the coupling plates tend to be displaced, electronic components at the bottom side wall of the circuit board, if any, may be damaged by the coupling plates during transportation of the computer.